ANSI 3543 Chapter 9

How is NPU calculated?

(Body N with test protein) - (Body N with protein free diet) / Total N intake

What is the job of immune antibodies?

protect the animal against specific infections

principal dry matter constituent in animal tissues

protein - protein or it's building blocks (AA) must be provided in the diet

What are apparent functions of chondroitin sulfates?

protein complexes of sulfated polysaccharides type A, B, C - cartilage, tendon, skin are high in chondroitin sulfates complexed with protein

What is kwashiorkor? Where in the world is it a problem?

protein deficiency in young children, "first-second" - child weaned from mothers milk when next child is born - causes decrease in blood proteins which results in bloated bellies and thin limbs - problem in developing nations where diets contain mainly starchy, low protein foods

What is digestible protein?

protein disappearing from ingesta as it passes down GIT

digestion in the stomach

protein enters the stomach, is denatured by HCl and is broken down to polypeptides by pepsin.

What are prions?

proteinaceous infectious particles that lack nucleic acids - composed almost entirely of normal cellular protein - appear to multiply by converting normal proteins to abnormal ones through changes in shape

What are all enzymes and many hormones made of?

proteins critical to survival - do not really contribute to total body protein content

What are "bypass" or "escape" proteins?

proteins incompletely digested by the rumen and pass into the small intestine partially intact - subjected to further hydrolysis by host enzymes

What do the keratins do? Why are they of limited value as protein supplements?

proteins of hair, wool, feathers, hooves, horns, beaks, and claws - resistant to acid, alkali, heat treatment, and especially breakdown by digestive enzymes - limited value because they cannot be easily digested unless processed

What appears to be the major job of myofibrilar proteins?

proteins of sarcoplasm or the material extracted from finely homogenized muscle with dilute salts - muscle metabolism and growth

What is a glycoprotein?

proteins with carb complexes arising from the acceptance of sugars by AA residues in polypeptide chain

What are the advantages of PER?

provides best estimate of protein value since only weight gain and protein consumed in a time period of 2-3 weeks are needed

essential components of amino acids

- carboxyl group (COOH) - amino group on adjacent carbon (NH2) - R group representing the rest of the chain

Describe the pros and cons of common protein sources for animals.

- cereal proteins are low in protein and lysine - oilseeds are 20-50% CP and are good lysine sources - oilseed meals are 30-50% CP and are good lysine sources - animal proteins are from 12-90% CP and are very good lysine sources - milling byproducts are variable in CP and moderate in lysine - forages range from 3 to 30% CP and are low in lysine

What two major factors determine the nutritive value of dietary protein?

- degree of absorption of individual AA (determined by hydrolysis effeciency) - balance of absorbable AA

Compare the site of action of enzymes (in relation to their elaboration) to that of hormones.

- enzymes are restricted within the cell or the immediate space around the site of elaboration - hormones are carried in the bloodstream from the release site to the target organ so they have a much wider range - not all hormones are proteins

What do proteolytic enzymes do and where do they come from?

- hydrolyze dietary proteins - come from epithelial cells lining lumen of GIT and pancreas

How is a protein made?

- join AA w/ peptide bonds to make chain - elongate chain until you have desired product

protein and AA toxicity

- some AA are toxic when fed at high levels, like methionine - it is possible to overfeed proteins

Describe the location of proteins in plants.

- stern has very little and it is poorly digested - leaf has most of what we find in forages - seeds

How much collagen is found in muscle tissue?

6%?

protein sythesis requirements

1. AA: 20-22 both EAA and nonEAA are required so you feed required EAA amount and some extra proteins over/above what is needed 2. energy in the form of ATP 3. nucleic acids which are synthesized by cells - process is very fast

What are the chemical and enzymatic actions necessary in the gut to digest proteins?

1. HCl (chemical) and pepsin in the stomach. 2. Rennin is important in the stomach of the young animal. 3. Proteolytic enzymes secreted by epithelial cells lining the intestinal tract. 4. Enzymes from the pancreas

How do we measure protein in ration balancing?

1. amount per animal per day in g, kg, or lbs 2. percent of the diet

What are the steps in the conversion of dietary protein to tissue protein?

1. intact dietary protein hydrolysis in the GIT (catabolism) 2. AA in intestinal lumen absorption from the GIT 3. AA in blood synthesis in tissues (anabolism) 4. intact tissue proteins

In order to properly feed protein we must know two things. What are they?

1. the minimum protein needs for the animal 2. the specific amino acid requirements for the animal

What are the three main sources of the amino acids found in the digestive tract of animals?

1. those deriving from dietary ingestion 2. those recycled along with other nitrogenous substances returned to the lumen of the intestinal tract: digestive enzymes, bile, sloughed cells 3. those synthesized by microbes residing in the lumen of the digestive tract

What are the three major things that happen to amino acids after absorption?

1. tissue protein synthesis: within 5-10 min after absorption from the gut, AA move into the cell and are used for protein synthesis 2. synthesis of enzymes, hormones, and other metabolites to participate in digestion, metabolism immunity, heredity, and endocrine function 3. deamination or transamination and use of carbon skeleton for energy by krebs cycle

How much of the energy expenditure in the body is required to keep a balance between protein synthesis and protein degradation in the body?

15 to 22%

Name some NPN compounds other than urea.

AA, peptides, amines, amides, nucleic acids

Why do animals have a poor ability to balance protein intake with the requirements of their bodies?

Animals eat to satisfy energy requirements so if protein as a percent of the ration isn't high enough they will fail to get enough total protein in the diet.

Which body tissues are prions found in? Why have slaughter house meat byproducts been banned from the diets of ruminants?

Brain and nervous tissue - believed that consumption of food/feed products containing these tissues from infected animals could be a possible route of transmission - transmission sort of unclear though

What is the elemental composition of typical protein?

C 53% H 7% O 23% N 16% S and P less than 1% - the 16% N is VIP for calculating protein levels with the kjeldahl method

feeds with bypass proteins

Grass silage, Whole soybeans (unprocessed), Extruded whole soybeans, Soybean meal, Com grain, Brewers grains, Distillers dried grains, Com gluten meal

Generally speaking, when is the only time that whole proteins are absorbed across intestinal epithelium? What is the mechanism for absorption?

In early postnatal life by pinocyctosis

essential amino acids

Methionine (partially replaced w/ cystine) Argnine Threonine Tryptophan Histidine Isoleucine Lysine Leucine Valine Phenylthalanine (partially replaced by tyrosine)

How do we measure true digestibility of protein? What is the problem with it?

N intake - (N feces - N metabolic)/N intake - problem: very difficult to measure metabolic N

How do we measure apparent digestibility of protein? How good is it as a measure of quality?

N intake -(N feces)/N intake - problem: not all N in the feces is from the diet, it also comes from metabolic processes, cell turnover, and enzymes - doesn't measure quality, just quantity

How is it that some nondietary essential AA can replace some of the need for dietary essential AA?

Several amino acids, though not EAA themselves, are synthesized from essential amino acids. Many amino acids are precursors or supply part of the structure of other metabolites.

In one sentence summarize the work of "metabolically active peptides and polypeptides."

These are large proteins/polypeptides that have been identified as important in modulating growth and other metabolic activites with varying concentrations in tissues depending on age, diet, and physiological factors.

Name some known diseases caused by prions.

Transmissible spongioform encephalopathies: scrapie in sheep/goats, creutzfeldt-jakob disease, bovine spongioform encephalopathy, chronic wasting disease in deer and elk

Give the definition of BV. How is it as a measure of quality?

a measure of the relationship of N retention to N absorption or the percent of absorbed N that is available for body use - a perfect protein would have a BV = 100% - good measure of quality

Why do dietary deficiencies of individual essential amino acids cause the same general symptoms?

a single AA deficiency prevents protein accretion in the same way that a shortage of a particular link in the chain prevents elongation of the chain

What are the three proteins that take part in muscle contraction?

actin, myosin, tropomyosin B

Amino acids are absorbed from the gut by

active transport

What are the major blood proteins?

albumin, alpha/beta/gamma globulins, thromboplastin, fibrinogen, conjugated protein hemoglobin, apoproteins A/B/E in various isoforms

For all conditions, which is the best measure of protein utilization?

all have limitations but probably PER

amino acids

all proteins composed of amino acids - over 200 in nature, but only 20-22 are commonly seen in proteins - up to 10 are dietary essentials - arrangement of AA and length of chain determine composition and function of protein

Explain how feeding multiple sources of protein that each have poor BV can be a good strategy?

although they have poor BV when fed alone, together they will have a high BV and therefore similar to a high value protein

What form do proteins have to be broken down to in order to be absorbed?

amino acid fragments

Using the form, x +y + 2 = Q+ B = urea, describe the urea cycle. Just use words instead of letters: Ammonia +carbon dioxide (keep going).

ammonia + CO2 + phosphate group from ATP = carbamyl phosphate + ornithine = citrulline

What do microbes in the gut degrade amino acids to?

ammonia, S, fatty acids, and CO2

Define anabolism and catabolism.

anabolism: synthesis catabolism: degradation - proceed simultaneously in animal tissues

Why is protein to calorie ratio important in the diet?

animals eat to satisfy energy requirements, so a reduced daily intake of a high calorie diet provides insufficient protein intake if % of protein is marginal - if calorie intake is insufficient, protein will be used for energy

What are the signs of protein deficiency?

anorexia, reduced growth rate, reduced or negative N balance, reduced efficiency of feed utilization, reduced serum protein conc, anemia, fat accumulation in the liver, edema, reduced birth weight, reduced milk production, reduced synthesis of enzymes/hormones

Where do the AA for body protein synthesis come from?

arise either from absorption from the GIT or synthesis with animal tissues by transamination

Define net protein accretion

balance between protein synthesis and protein degradation, both dynamic and metabolic processes - during growth

Explain the concept of ideal protein diets.

based on the formulation of biologically available AA mixtures that match quantitative AA requirements of animals in a given physiological state of growth and particular genotype

Why does urea contain more than 100% CP?

because it is 45% N, the high nitrogen level gives it a very high CP

Why is amino acid balance in the diet not of much concern in the ruminant?

because they can synthesize protein from nonprotein N sources and make what they need from the N and carb quantities - synthesize their own AA

What is the unique fact about cats and taurine?

beta sulfonic acid not present in proteins, cats are the only species known to require it - occurs as free AA in diet

Can D-isomers of amino acids be used by animals?

can be used for growth by most animals

What is citrullene's claim to fame?

can completely replace arginine in feline diets and some other species

Where are most body proteins found?

cell membrane components, muscle, supportive capacities in hair, skin, and hooves

Explain how amino acid deficient feeds/foods can be used in a balanced way

certain foods will be deficient in an AA, but when combined with a food that has those AA, the animal can get a balanced meal - corn deficient in lysine/tryptophan but containing methionine/cystine + soybean meal deficient in methionine/cystine but has lysine/tryptophan = balanced meal

Define an amino acid imbalance.

change in a proportion of dietary AA that has an adverse effect preventable by a relatively small amount of the most limiting AA

Name the major categories of tissue proteins your text discusses

collagen, elastin, myofibrilar proteins, contractile proteins, kertains, blood proteins, enzymes, hormones, metabollically active peptides and polypeptides, and immune antibodies

What are the three general ways we can accomplish the proper feeding of proteins?

combine individual feed proteins or supplement protein with individual amino acids to provide both quantity and quality of protein for the animal's needs

List the important mucoproteins briefly discussed in the text.

complexes of protein with AA sugars glucosamine and galactosamine, mannose/galactose, pentose, fructose, and sialic acid - mucous secreations - salivary secreations to inhibit agglutination of RBCs by influenza - containing mannose/galactose

What are the functions that could force us to put glutamine on the essential amino acid list?

conditional metabollic requirements for the intestinal mucosa during illness - normal GIT immune function - normal metabolism of pancreas and liver

What happens to other amino acids if one is deficient?

deamination of remaining AA, loss of ammonia as urea, use of carbon chain for energy

why do tissues differ in rate of protein synthesis?

depends on concentration of RNA

What is PER?

determined by conducting a feeding trial, protein sources are compared in terms of animal body weight gain per gram of protein or nitrogen fed. - body wt. gain, g / protein consumed, g

What does the concentration of RUP (rumen undegraded protein) depend on?

dietary protein concentration and level of intake

Proteins can be characterized nutritionally on the basis of

digestibility, absorbability, and degree of AA utilization after absorption

What are the three factors affecting the degree of utilization of feed proteins?

digestibility, absorption, and utilization of component AA after absorption

What is the relationship between leaf:stem ratio and protein?

directly correlated - as leaf:stem ratio goes down, protein goes down

Which species do we know to require arginine as adults? What are the deficiency symptoms?

dogs and cats develop tremors, hyperammonemia, high urinary orotic acid levels when fed deficient diets

What natural protein has the best BV?

egg protein

How is elastin different from collagen?

elastin is stretchy but breaks easily when stretched to it's elastic limit, minor component of muscles

How is BV determined? What is the formula?

experimentally by measuring the total N intake and N losses in urine and feces (N intake - [fecal N + urinary N] / N intake - fecal N) x 100

True or False. Protein is a metabolic requirement.

false, only AA requirement

If I say a protein has high nutritive value, what do I mean?

good balance among its EAA composition

At which life stage is dietary protein requirement the highest for an animal? Why?

highest in young animals to support new tissue growth - declines to tissue maintenance levels with maturity - pregnancy or lactation causes boost in protein requirements

In which species do adults need dietary histidine?

humans

How many enzymes are found in animal cells?

hundreds, each with a specific structure and distinct reactive group

What are some of the major jobs of enzymes?

hydrolytic digestive enzymes, degradative metabolic rxns, synthetic processes

Dipeptidase

in brush border of small intestine - cleaves dipeptides.

Aminopeptidase

in brush border of small intestine - cleaves single amino acids from N end

How does urea exit the body in mammals?

in the urine

What is the practical significance to browning reactions in feedstuffs?

increase in bypass proteins - if hay is too wet when put up it may heat and browning can occur, the degree of heat damage can be measured by measuring ADF-N - as ADF-N increases, the protein availability decreases - can also happen in silage making if the material gets too hot in the fermentation process (100° -120°F) perhaps because of poor packaging or dry material being ensiled - browned feeds have a sweet tobacco odor, are dark brown, and are generally eaten well by livestock.

Name some important protein hormones.

insulin, growth hormone, gonadotrophic hormone, parathyroid hormone, and calcitonin

Define protein quality.

is the measure of the ability of a protein to supply the essential amino acids in the proper quantity and ratio needed by an animal for maintenance and production

How does collagen affect the toughness of cooked meat?

it increases the toughness because of it's shrinkage on heating as a result of high proline and hydroxyproline content

What is kwashiorkor? Describe it

it is protein deficiency affecting pigs and humans characterized by small sature, low serum protein content, anemia, and edema

Where does the protein found in the lower gut of the ruminant come from?

it is the sum of protein that escaped rumen fermentation and microbial yield

What happens to ammonia that is released in the rumen?

it may be absorbed through the rumen or the lower GIT for use at the tissue level in AA synthesis or in the liver for urea synthesis

What is unique about the cat's requirement for sulfur-containing amino acids?

it require taurine because of this - when fed no taurine and low sulfur diets, they develop retina degeneration

Why is feeding excessive protein to ruminants not a good idea?

it will be absorbed and wasted as urea lost in the urine

If l fed a perfect protein to a ruminant, would it be better or worse after going through the rumen?

it will be worse - low quality proteins will improve - proteins supplied to the GIT are remarkably constant

EAA most likely to be deficient in farm animals

leucine (first limiting AA), tryptophan, threonine, methionine

peptide bonds

link amino acids by coupling the carboxyl group with the amino group of another AA w/ hydolysis - formation requires 20 biochemical rxns and hundreds of supporting rxns - 1 bond = 7 ATP

What are some ways of creating protected feed proteins?

lipid encapsulation, chemical derivitization, or use of inhibitors of microbial acid demanination

What is the function of myelin?

lipoprotein abundant in nervous system as sheath around nerve fibers - peripheral 80%, central 35%

Where does the urea cycle take place?

liver and to a lesser degree, intestinal cells

Where in the body are amino acids degraded?

liver for the majority, but also small intestinal cells

lipoproteins

made by fatty acids and other lipids absorbed into the surface of blood serum proteins - protein content 2-50% - redistribute lipids to help prevent heart disease

myosin

major components of thick filaments in striated muscle - important role in enzyme activity of ATPase

Do rumen bacteria require ammonia?

many do, yes

What is NPU?

measures efficiency of growth by comparing body N resulting from feeding a test protein with that resulting from feeding a comparable group of animals a protein-free diet for the same length of time - large number of values can be obtained over a brief test period with a minimum of measurements

What are the functions of the membrane proteins of animal cells?

membrane composed of proteins, lipids, carbs in various proportions -permeability barrier - transport substances across the interior/exterior cell boundary - supports catalytic function - other important, less defined functions

nonessential AA

metabolically essential but body synthesizes them Alanine Aspartic acid Glutamic acid Tyrosine Citrulline Cystine Praline Glycine Hydroxyproline Serine

Why is protein deficiency so common?

most energy sources are low in protein and supplements are expensive

Where are blood proteins synthesized?

most in the liver - rate varies from minutes to days, even weeks

uric acid toxicity

much less toxic than urea and requires less water to dilute and excrete it

What are erythocytes membranes made of?

mucolipids, phospholipids, loosely bound proteins

Why is albumin considered to be such a good dietary protein?

nearly ideal AA composition and high digestibility

What is NPV?

net protein value: takes into account differences in digestibility between proteins and would presumably be better - BV x digestion coefficient

Is feeding excess protein generally a good thing from a metabolic point of view?

no - can cause weight depression, dull hair coat, change liver water and protein content, etc

tropomyosin B

no enzymatic properties and does not combine in soln with actin or myosin

does any diet provide the precise required quantity of AA?

no, and it is far more cost efficient to feed slight to large excess quantities than to purchase specific protein supplements in order to precisely measure it out - excess AA can be deaminated and catabolized into other AA

If l have a feed with low protein content of poor quality should I expect much of it to end up as RUP?

no, high-quality high-protein feeds will have a higher RUP

Can ruminants produce maximally receiving only NPN?

no, microbial synthesis of limiting AA is insufficient to meet the needs for production of muscle protein and milk in genetically superior animals

Does strenuous exercise warrant an increase in dietary protein requirement?

no, the efficiency of protein metabolism may actually be improved as a result of exercise

Are amino acids produced from recycled N of any consequence to animals?

no, they are the same

Where does metabolic fecal nitrogen come from?

normal metabolism of tissue protein and includes N from sloughed cells from intestinal lining, residues of digestive enzymes, substances secreted into the lumen of the GIT

Is arginine required in the diet of all species for maximum growth?

not required for maintenance in most species

protein sythetic enzymes under

paracrine, endocrine, and autocrine control

What is the reason that the effects of excess consumption of individual acids has been studied?

partially due to genetic disorders where individuals lack certain enzymes to metabolize AA

Compare the mode of body acquisition of passive immunity versus active immunity.

passive: colostrum, placental transfer, parenteral injection active: exposure to pathogen and subsequent anitbody production/immunity

What are proteins degraded to in the rumen?

peptides or amino acids which will be further degraded into organic acids, ammonia, and CO2

Is there any reason to feed intact protein as well as NPN to ruminants?

performance increases when fed intact proteins

amino acid imbalance

presence of all the essential amino acids is necessary for protein synthesis and the balance of amino acids available must be correct - better the balance the better the protein. - the closer the dietary protein to the proportions required by the animal, the better the dietary protein will be used by the body for the manufacture of new protein.

What is amino acid antagonism? How is it different from an imbalance?

refers to growth depression that can be overcome by supplementation with an AA structurally similar to the antagonist - different because the supplemental AA need not be limiting

What is deamination?

removal of the amino group from the carbon skeleton of the amino acid and entrance of amino group into the urea cycle

elastin

resembles denatured collagen and is made of long, randomly ordered polypeptide chains - stretchy - found in combination with large amounts of collagen in ligaments/arteries where it can restore original tissue shape/position - insoluble in water and resistant to digestive enzymes

Why does ruminant feeding strategy focus on providing a diet that serves the N needs of the microbial population as well as the amino acid needs of the host animal?

ruminants are able to use nonprotein N to derive much of their protein requirements due to microbes - reduce cellulose and produce short chain fatty acids for energy - synthesize AA and protein from inorganic N or recycled N - so you tailor to the diet to the animal and microbes because the microbes will synthesize much of the dietary requirements of the animal

pepsin

secreted by the gastric mucosa as pepsinogen - pepsinogen is activated to pepsin by HCI at pH of approximately 2 - cleaves proteins at aromatic AA - also activated by HCI.

Elastogen (pancreatopeptidase)

secreted by the pancreas - activated to elastase by trypsin - cleaves polypeptides at valine, leucine, serine, and alanine in the lumen - optimum pH 8.8

Carboxypeptidogen A and B

secreted from the pancreas - activated by trypsin - both are termed exopeptidoses because they cleave off single amino acids (AA) from the COOR end - optimum pH 7.5 -8.0.

chymotrypsin A, B, C

secreted from the pancreas - activated to chymotrypsin by trypsin - cleaves polypeptides to peptides at tyrosine, tryptophan, and phenylalanine - occurs in the lumen of SL

trypsinogen

secreted from the pancreas - activated to typsin by enterokinase from the small intestine mucosa - cleaves polypeptides to peptides at lysine and arginine in the lumen. - Optimum pH 7.6-8.0.

rennin

secreted in young milk-fed ruminants in the gastric juice and breaks down milk protein. - activated by HCI.

Why do we know that it is the carbon skeleton of the essential amino acids that is the "essential" part?

several EAA can be replaced by their corresponding alpha-hydroxy or alpha-ketoanalogs: animal is unable to synthesize skeleton

Names some factors that influence protein requirements.

sex, species, and genetic makeup within species - males generally have higher requirement

conjugated proteins

simple proteins combined with nonprotein substance (prosthetic group) such as phosphoric acid, carbohydrate, or nucleic acid - includes: nucleoproteins, glycoproteins, mucoproteins, lipoproteins, chromoproteins,metalloproteins, and phosphoproteins.

What are the adverse effects of excess amino acid consumption?

slight intake supression followed by a return to normal followed by a large supression of feed intake, tissue damage, death

In what form is N excreted from the body?

sloughed cells of the intestinal lining, residues of digestive enzymes, and substances secreted into the GIT lumen

What does efficient NPN use depend on?

solubility of the NPN and availability to the microflora of readily available carbs

Based on the absorption mechanisms of amino acids from the gut, why is it that high dietary concentrations of amino acid X can increase the requirement for amino acid Y?

some AA compete with each other for transport

What is the source of protein fermented in the large intestine? Describe any problems this may cause.

source is sloughed mucosal cells and protein not digested earlier - NPN is incorporated into microbial protein that causes problems in interpreting digestion trials on proteins because we cannot distinguish one protein from the other

What is transamination?

transfer of an amino group from 1 amino acid to the carbon skeleton of a keto acid

Name important "specialized functions" of proteins in the body. Note to student: Be sure to consult text Table 9.3 when you answer this.

structural functions as well as roles in gene expression, enzyme catalyzed rxns, protection, muscle contraction, metabolic regulation, storage of O2/nutrients, cell structure, transport of nutients and O2, and immune function

How can milk production be improved in a dairy cow receiving only NPN?

supplement methionine, lysine, and other AA or just feed it a normal damn diet

In general terms, what do polypeptide growth factors (PGF's) do in the body?

take part in growth regulatory processes moreso than other growth hormones - influence protein metabolism, development and maintenance at cellular, tissue, and organ levels

Define BV. Why is it a good tool for evaluating a feed protein?

the % of N absorbed from the GIT that is available for productive body functions - good tool b/c it tells you the bioavailability of the protein

Why are alanine, cysteine, serine, etc. not dietary essentials?

the AA and their carbon skeletons can be synthesized by skeletal muscle, liver, brain, adipose tissue, intestine, kidney, lung, placenta, lactating mammary glands, and other tissues

What is the basis for classifying AA as essential or nonessential?

the ability of an animal tissue to synthesize the AA from other compounds

How is an amino acid toxicity different from an amino acid antagonism?

the adverse effect of an AA in excess cannot be overcome by supplementation with another AA - difference is that it cannot be overcome

What is apparent protein digestibility?

the difference between what is in the feed and what is in the feces - includes both unabsorbed and metabollic fecal N

Speculate as to why nonruminant omnivores have more exacting AA requirements than some nonruminant herbivores.

the differences in the degrees if microbial fermentation - hind gut fermenters are more similar to ruminants

Describe the basis of the symbiotic relationship of animals and the microbes that live in their digestive tracts.

the microbes supply AA for use by the host animal and the animal provides friendly environment for microbes - microbes require ammonia, sulfur, and carbon source

what if the ruminant is not eating enough rumen degradable proteins?

the microbes will stop fermenting fiber and therefore the animal stops digesting

If protein and amino acids enter the small intestine of the ruminant, what happens to them?

their digestion and absorption is similar to that of nonruminants

Why do you think that enzymes are called "organic catalysts"?

they are completely protein in nature, specific in their rxns

Why can adult ruminants live with no protein at all in their diet?

they can depend entirely on nonprotein N in their diet because of the microbes - mircobes synthesize AA and protein from nonprotein N - can themselves be utilized as a source of protein

What do chain length and amino acid sequence have to do with the characteristics of a protein?

they define the characteristics and function of the protein

Why are dietary proteins that do not contain a good essential amino acid profile poorly used for tissue protein synthesis?

they have a deficiency or imbalance of 1+ AA

collagen

triple helix w/ banded mcl - compact and very strong - content increases with aging - water insoluble and resistant to digestive enzymes

Are there any specific deficiency symptoms associated with specific amino acids?

tryptophan: eye cataracts threonine/methionine: fatty liver lysine: abnormal feathering

What does the rumen escape of protein depend on?

type of protein and rate of degradation

In what form is N excreted in birds?

uric acid

What is the molecular weight of proteins?

vary considerably in their chemical composition, physical properties, shape, solubility, and biological function b/c their size - can be mw of 5,000 to many millions - most 35,000 to 500,000

actin

when extracted from myosin, it is in the globular form when ATP present - this polymerizes on the addition of neutral salts to give chainlike mcls of fibrous actin while changing ATP to ADP and liberates inorganic P - reverse process occurs w/o ATP

Under what circumstances will the body use protein for energy?

when provided in excess of metabolic requirement or when calorie intake is insufficient

Can feeding a pure amino acid source improve the NPU of a protein source?

yes

Do organs and tissues have unique protein turnover rates in the body?

yes

Can ruminants survive and produce if the only N they receive is in the form of NPN?

yes, NPN will be used in the rumen for AA synthesis for both dairy and beef cattle

Can NPN be the primary nitrogen source in a ruminant ration?

yes, but performance of ruminants is increased when protein is supplemented

Can alpha-keto acids be used by animals? How?

yes, by forming corresponding L-AA by transamination

Are proteins being synthesized and degraded at the same time in the body?

yes, continually and simultaneously

Can the N recycled from the body back into the gut be acted upon by microbes?

yes, it is subject to the same microbial action as ingested N

If protein "escapes" degradation in the rumen is this a good thing?

yes, it will be utilized in the small intestine if it contains lots of EAA

simple proteins

yield a-amino acids or their derivatives on hydrolysis - globular: smaller than fibrous proteins and each consists of a compactly-folded peptide chain/s, soluble in most everything - fibrous: insoluble animal proteins, composed of extended or coiled peptide chains, highly resistant to digestion by proteolytic enzymes, called scleroproteins or alburninoids. ex - collagen, elastin, and keratin.

How has recombinant DNA technology changed the traditional way we balance rations for their amino acid needs?

you can genetically alter feed to contain the AA it is usually deficient in so it becomes a sort of super food